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1.
C. M. Valdez K. C. Nishikawa 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1997,180(3):187-202
This study investigates how visual and tactile sensory information, as well as biomechanical effects due to differences in
physical characteristics of the prey, influence feeding behavior in the frog Cyclorana novaehollandiae. Video motion analysis was used to quantify movement patterns produced when feeding on five prey types (termites, waxworms,
crickets, mice and earthworms). Twelve kinematic variables differed significantly among prey types, and twelve variables were
correlated with prey characteristics (including mass, length, height and velocity of movement). Results indicate that C.␣novaehollandiae uses a different strategy to capture each prey type. Visual assessment of prey characteristics appeared to be more important
in modulating feeding behavior than tactile cues or biomechanical effects. We propose a hierarchical hypothesis of behavioral
choice, in which decisions are based primarily on visual analysis of prey characteristics. In this model, the frogs first
choose between jaw prehension and tongue prehension based on prey size. If they have chosen jaw prehension, they next choose
between upward or downward head rotation based on length and height of the prey. If they have chosen tongue prehension, they
next choose between behavior for fast and slow prey. Final decisions may be the result of behavioral fine tuning based on
tactile feedback.
Accepted: 5 August 1996 相似文献
2.
We test predictions about differences in the foraging behaviors of male and female giraffes (Giraffa camelopardalis tippelskirchi Matchie) that derive from a hypothesis linking sexual size dimorphism to foraging behavior. This body-size hypothesis predicts
that males will exhibit specific behaviors that increase their dry-matter intake rate relative to females. Foraging behavior
was examined at two hierarchical levels corresponding to two spatial and temporal scales, within patches and within habitats.
Patches are defined as individual trees or shrubs and habitats are defined as collections of patches within plant communities.
Males were predicted to increase dry-matter intake rate within patches by taking larger bites, cropping bites more quickly,
chewing less, and chewing faster. Within habitats, males were expected to increase intake rate by increasing the proportion
of foraging time devoted to food ingestion as opposed to inter-patch travel time and vigilance. The predictions were tested
in a free-ranging population of giraffes in Mikumi National Park, Tanzania. Males spent less total time foraging than females
but allocated a greater proportion of their foraging time to forage ingestion as opposed to travel between patches. There
was no sex difference in rumination time but males spent more time in activities other than foraging and rumination, such
as walking. Within patches, males took larger bites than females, but females cropped bites more quickly and chewed faster.
Males had longer per-bite handling times than females but had shorter handling times per gram of intake. Within habitats,
males had longer average patch residence times but there was no significant sex difference in inter-patch travel times. There
was no overall difference between sexes in vigilance while foraging, although there were significant sex by habitat and sex
by season interactions. Although not all the predictions were confirmed, overall the results agree qualitatively with the
body-size hypothesis. Sex-related differences in foraging behavior led to greater estimated intake rates for males at the
within-patch and within-habitat scales.
Received: 20 November 1995 / Accepted: 5 November 1996 相似文献
3.
Non-consumptive effects of larval Salamandra on crustacean prey: can eggs detect predators? 总被引:3,自引:0,他引:3
Leon Blaustein 《Oecologia》1997,110(2):212-217
Predators affect prey populations not only by prey consumption but also in nonconsumptive ways including modifying prey behavior.
I tested the effects of fire salamander larvae (Salamandra infraimmaculata) on populations of co-occurring crustacean species in artificial outdoor pools. I also tested whether these effects were
due entirely to prey consumption by Salamandra larvae or alternatively to some nonconsumptive effect. The soil (containing crustacean eggs) added to the artificial pools
was collected from a dried-out temporary pool that is inhabited by Salamandra during the early part of the hydroperiod. I randomly assigned the pools to one of three treatments: control, free Salamandra, or caged Salamandra. Free salamander larvae could roam the entire pool and prey upon crustaceans. Caged salamander larvae were placed within
a cage with having 250-μm mesh windows. They could not prey upon the crustaceans but could, for example, influence them by
chemical cues. Densities of the three dominant crustacean species (Arctodiaptomus similis, Ceriodaphnia quadrangula and Cyzicus sp.) were drastically reduced in both salamander treatments compared to the control. Crustacean densities, however, were
not significantly different between the two salamander treatments. One plausible explanation is that crustacean eggs can detect
the presence of this predator via chemical cues and delay hatching.
Received: 4 March 1996 / Accepted, 23 October 1996 相似文献
4.
Effects of ultraviolet radiation on early larval stages of the Alpine newt, Triturus alpestris, under natural and laboratory conditions 总被引:3,自引:0,他引:3
Although Alpine newts (Triturus alpestris) are found at altitudes up to 2500 m, their larvae proved to be extremely sensitive to UV radiation when exposed in clear
tapwater to natural sunlight or to comparable artificial UV-B radiation in the laboratory. The experiments revealed severe
skin damages (lysis of epithelial cells) and mortality after a few days of exposure. In their natural habitats above the timberline,
however, the larvae are protected by the high concentration of dissolved organic carbon in the water leading to an almost
complete absorption of UV radiation within the first few centimeters of the water layer. Furthermore, when exposed to UV radiation
larvae show erratic swimming activities that may carry them into protected areas. Only in very shallow natural habitats did
we detect sublethal UV-like histological effects. Shallow high mountain ponds with clear water normally lack newt populations,
probably as a consequence of both low temperature and the effects of UV radiation.
Received: 4 October 1996 / Accepted: 7 February 1997 相似文献
5.
Stuart I. Cromarty Charles D. Derby 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1997,180(5):481-491
The aim of our paper was to investigate whether single olfactory receptor neurons (ORNs) of the spiny lobster Panulirus argus functionally express more than one type of receptor, examine the consequences of this on coding of mixtures, and compare
principles of odorant mixture coding by spiny lobsters with that by the channel catfish, which has been studied extensively
using the same experimental and analytical procedures (Caprio et al. 1989; Kang and Caprio 1991). We examined responses of
individual taurine-sensitive ORNs to binary mixtures of excitatory compounds, either competitive agonists (taurine, β-alanine,
hypotaurine) or non-competitive agonists (taurine, l-glutamate, ammonium chloride, adenosine-5′-monophosphate). Responses to mixtures were compared to two indices: mixture discrimination
index (MDI) and independent component index (ICI). Binary mixtures of competitive agonists had MDI values close to 1.0, as
expected for competitors. Mixtures of non-competitive agonists had ICI values averaging 0.83, indicating the effects of the
components are not independent. We conclude that individual olfactory cells of spiny lobsters can express more than one type
of receptor mediating excitation, one of which typically has a much higher density or affinity, and that spiny lobster and
catfish olfactory cells encode mixtures of two excitatory agonists using similar rules.
Accepted: 20 December 1996 相似文献
6.
Jonas Dahl 《Oecologia》1998,117(1-2):217-226
I assessed the impact of both vertebrate and invertebrate predators on a lotic benthic community in a 1-month-long experiment,
using enclosures containing cobble/gravel bottoms, with large-mesh netting that allowed invertebrates to drift freely. Brown
trout (Salmo trutta) and leeches (Erpobdella octoculata) were used as predators and four treatments were tested: a predator-free control, leeches only, trout only, and leeches and
trout together. A density of 26.7 leeches/m2 (20 leeches/enclosure) and 1.3 trout/m2 (one trout per enclosure) was stocked into the enclosures. The total biomass of invertebrate prey was significantly lower
in the trout and trout plus leech treatments than in the leech and control treatments, which were due to strong negative effects
of trout on Gammarus. On the individual prey taxon level, both trout and leeches affected the abundance of Asellus
,
Baetis and Ephemerella, whereas the abundance of Gammarus was only affected by trout, and the abundance of Orthocladiinae and Limnephilidae was only affected by leeches. In the treatment
with trout and leeches together, the abundance of Ephemerella and Baetis was higher than when trout or leeches were alone, which was probably due to predator interactions. Leeches and trout had
no effects on prey immigration but did affect per capita emigration rates. Both trout and leeches indirectly increased periphyton
biomass in enclosures, probably due to their strong effects on grazers. Both trout and leeches were size-selective predators,
with trout selecting large prey, and leeches selecting small prey. Size-selective predation by trout and leeches affected
the size structure of five commonly consumed prey taxa. Trout produced prey populations of small sizes owing to consumption
of large prey as well as increased emigration out of enclosures by these large prey. Leech predation produced prey assemblages
of larger size owing to consumption and increased emigration of small prey. These results suggest that in lotic habits, predatory
invertebrates can be as strong interactors as vertebrate predators.
Received: 23 June 1997 / Accepted: 4 May 1998 相似文献
7.
Food web analysis of southern California coastal wetlands using multiple stable isotopes 总被引:16,自引:0,他引:16
Carbon, nitrogen, and sulfur stable isotopes were used to characterize the food webs (i.e., sources of carbon and trophic
status of consumers) in Tijuana Estuary and San Dieguito Lagoon. Producer groups were most clearly differentiated by carbon,
then by sulfur, and least clearly by nitrogen isotope measurements. Consumer 15N isotopic enrichment suggested that there are four trophic levels in the Tijuana Estuary food web and three in San Dieguito
Lagoon. A significant difference in multiple isotope ratio distributions of fishes between wetlands suggested that the food
web of San Dieguito Lagoon is less complex than that of Tijuana Estuary. Associations among sources and consumers indicated
that inputs from intertidal macroalgae, marsh microalgae, and Spartina foliosa provide the organic matter that supports invertebrates, fishes, and the light-footed clapper rail (Rallus longirostris levipes). These three producers occupy tidal channels, low salt marsh, and mid salt marsh habitats. The only consumer sampled that
appears dependent upon primary productivity from high salt marsh habitat is the sora (Porzana carolina). Two- and three-source mixing models identified Spartina as the major organic matter source for fishes, and macroalgae for invertebrates and the light-footed clapper rail in Tijuana
Estuary. In San Dieguito Lagoon, a system lacking Spartina, inputs of macroalgae and microalgae support fishes. Salicornia virginica, S. subterminalis, Monanthochloe littoralis, sewage- derived organic matter, and suspended particulate organic matter were deductively excluded as dominant, direct influences
on the food web. The demonstration of a salt marsh–channel linkage in these systems affirms that these habitats should be
managed as a single ecosystem and that the restoration of intertidal marshes for endangered birds and other biota is compatible
with enhancement of coastal fish populations; heretofore, these have been considered to be competing objectives.
Received: 24 April 1996 / Accepted: 24 October 1996 相似文献
8.
Many studies have experimentally addressed the effects of a particular predator species on prey behavior. In nature, however,
prey frequently face multiple species of predators that often vary in their predatory mode and in their level of predation
risk. Relatively few studies have considered prey responses under these complex conditions. In Kentucky, the stream-dwelling
water strider (Aquariusremigis) coexists with many potentially dangerous predators, two of which are the green sunfish (Lepomiscyanellus) and the fishing spider (Dolomedesvittatus). Green sunfish occupy stream pools and attack water striders from below. In contrast, fishing spiders hunt along stream
shorelines where they perch on overhanging vegetation or rocks and attack water striders near shore. We compared how A. remigis individuals respond to these two very different predators in pools with one or both predators. The presence of sunfish in
pools had strong effects on male water strider behavior, including increased use of three types of refuge from sunfish (riffles,
climbing out of the water, sitting on the water but at the edges of pools), decreased activity and a decreased number of aggressive
males on the water. Spiders also influenced water strider behavior; male water striders avoided spiders by shifting away from
the edges of pools. Comparisons of the effects of the two predator species showed that in general, antipredator responses
by male water striders were stronger in pools with fish alone than in those with spiders alone. In the presence of both predators,
male water strider behavior (microhabitat use and activity) was generally similar to behavior in the presence of fish alone.
In contrast, female water striders showed no significant response to the presence of sunfish, and little response to the presence
of spiders. This lack of response could be because females spent much of their time in refuges even in the absence of predators
(apparently hiding from harassment by males). Both spiders and fish caused decreases in water strider mating activity. The
presence of fish reduced both the number of matings per pool (mating frequency), and mean mating durations. Spiders induced
a decrease in mean mating duration, but not in mating frequency. The largest reductions in mating activity occurred in pools
with both predators present. Pools with either spiders or fish alone suffered 15–20% water strider mortality during our experiment
(versus no mortality in predator-free pools). Extant theory suggests that when prey face conflicting microhabitat responses
to two predators (as in this study), the predators should have facilitative effects on predation rates (i.e., prey that avoid
one predator are often killed by the other and vice versa). Mortality rates in pools with both predators present, however,
were not significantly different from that predicted by a null model of multiple predator effects. The lack of predator facilitation
can be explained by the compensatory reductions in water strider activity and mating activity in the presence of both predators.
Received: 26 August 1996 / Accepted: 12 June 1998 相似文献
9.
The effect of light environment, leaf area, and stored carbohydrates on inflorescence production by a rain forest understory palm 总被引:2,自引:0,他引:2
Saul A. Cunningham 《Oecologia》1997,111(1):36-44
Variation in flowering by long-lived plants may be correlated with current resource availability. If, however, there are
trade-offs between current and future reproduction, or between reproduction and storage or growth, then understanding variation
requires a whole-plant, longer-term perspective. Inflorescence production by Calyptrogyne ghiesbreghtiana Linden ex. H. Wendl., an understory palm, was studied over 3 years. Annual inflorescence production varied greatly and was
correlated with variation in plant size and light environment. There was no trade-off between past inflorescence production
and the frequency of future inflorescence production. On the contrary, individuals that produced more inflorescences than
predicted from their size and light environment tended to continue to do so in subsequent years also. I manipulated the resource
environment of a subset of plants by removal of leaves and/or reproductive spikes. Leaf removal suppressed inflorescence production
for the following 2 years, but spike removal had no effect. One year after leaf removal stored reserves were, on average,
back to pre-treatment levels. There was, however, a negative effect of recent inflorescence production on storage. Plants
with higher levels of storage had higher inflorescence production in the next 75 days. In C. ghiesbreghtiana the resource cost of reproduction is apparent in short-term variation in stored reserves. In contrast, annual inflorescence
production does not follow a trade-off pattern between successive years, but consistently reflects both plant size and the
light environment.
Received: 20 October 1996 / Accepted: 25 January 1997 相似文献
10.
In this study we used pinfish (Lagodon rhomboides) in field experiments to examine linkages between intertidal saltmarsh and adjacent subtidal habitats. Pinfish are more
than twice as abundant in intertidal marshes adjacent to seagrass beds than in those adjacent to the unvegetated subtidal
bottom. Movement of pinfish between the marsh edge and the adjacent subtidal habitat was greater for fish captured in areas
with both intertidal and subtidal vegetation than in those with intertidal vegetation and adjacent unvegetated mudflats. This
movement provides an important link between habitats, allowing transfer of marsh-derived secondary production to subtidal
seagrass beds and vice versa. Pinfish held in enclosures with both intertidal and subtidal vegetation were, on average, approximately
90% heavier than fish held in enclosures with intertidal vegetation and unvegetated subtidal bottom. Because saltmarshes and
seagrass beds contribute to the production of living marine resources, active measures are being taken to preserve and restore
these habitats. The results from this study have direct application to decisions concerning site selection and optimal spatial
proximity of saltmarsh and seagrass habitats in the planning of restoration and mitigation projects. To maximize secondary
production and utilization of intertidal marshes, managers may opt to restore and/or preserve marshes adjacent to subtidal
seagrass beds.
Received: 31 May 1996 / Accepted: 23 October 1996 相似文献
11.
L. Tommasi G. Vallortigara M. Zanforlin 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1997,180(5):567-572
Young chickens were trained to find food by ground-scratching in the centre of a closed uniform arena and were then tested
in arenas of similar areas but of different shapes. Chickens showed localized searching behaviour in the square-shaped arena,
and maintained this behaviour when placed in a circular or triangular (both equilateral and isosceles) arena. With a rectangular-shaped
arena, obtained by doubling the original square-shaped one, chickens showed more dispersed searching along the major axis,
but searching tended to be concentrated around the centres of the composing squares and around the centre of the rectangle
itself. When trained in a square- or triangle-shaped arena and then tested in an arena of the same shape but a larger area,
chickens displayed searching behaviour at two different distances from the wall of the arena, one corresponding to the correct
distance (i.e. centre) in the smaller (training) arena, the other to the actual centre of the test arena. On the other hand,
in a circular arena, chickens searched mainly at a distance midway between the radius of the small (training) and of the large
(testing) circular arena. These results suggest that, during training, chickens encoded information on both the absolute and
the relative distance of the food from the walls of the arena, the latter information being more accurate when the arena displayed
identifiable features such as corners.
Accepted: 28 December 1996 相似文献
12.
T. Friedel F. G. Barth 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1997,180(3):223-233
Spiders can use air particle movements to localize moving prey. We studied the responses of 32 wind-sensitive interneurones
in the hunting spider Cupiennius salei to prey stimuli.
Stimulation with a tethered flying fly or with artificial air pulses activated plurisegmental interneurones that responded
to changes in air movement velocity and were thus well suited to represent the highly fluctuating air stream typical of prey
stimuli. In most interneurones (n = 18) the responses to the stimulation of different legs were not significantly different from each other.
Different interneurones had different response characteristics and their latencies largely overlapped suggesting that there
is parallel processing of the signals by populations of interneurones with different response characteristics.
In two interneurones the number of spikes and the spiking pattern elicited by stimulation of each of the eight legs markedly
differed depending on the leg stimulated. These neurones may play an important role in directional information processing.
Stimulation of the adjacent legs from front to back or from back to front revealed two interneurones sensitive to the direction
of successive stimulation of the legs. These neurones may be able to detect the motion of an air movement source in a preferred
direction and thus act as nearfield motion detectors to localize a moving prey item.
Accepted: 28 September 1996 相似文献
13.
M. Glagow J.-P. Ewert 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1996,180(1):1-9
This study confirms for a phylogenetically basal terrestrial vertebrate that dopaminergic modulations interfere with the
visually directed appetitive and consummatory feeding behaviors orienting and snapping, respectively. (1) In common toads
Bufo bufo, intralymphatic administration of the dopamine D2/D1-receptor agonist apomorphine led to a dose-dependent facilitation of prey-snapping in response to moving objects. The snapping
activity reached a maximum 15–35 min after apomorphine injection. (2) To changes in configurational stimulus features, the
basic pattern of discrimination was maintained; however, the acuity of discrimination was reduced due to the high snapping
response level. (3) The apomorphine-induced facilitation of snapping was accompanied by a suppression of prey-oriented lunging
and turning. Toads snapped only if prey occurred frontally in the visual field at a relatively short distance. The snapping
behavior was fixed in its form and stereotyped regarding its immediate release. (4) About 90 min after apomorphine administration,
prey-oriented turning behavior was restored and displayed a facilitatory rebound. (5) In comparative experiments with the
species B. marinus, both prey-oriented turning and snapping responses were suppressed by apomorphine in a dose-dependent manner. (6) After pre-treatment
with the dopamine antagonist haloperidol, apomorphine showed no measurable effect on the visual release of prey orienting
or snapping. (7) The results contribute to the sensorimotor and the motivation hypothesis of dopamine function proposed for
higher vertebrates and stimulate a comparative discussion of anatomic homologies and functional analogies.
Accepted: 10 July 1996 相似文献
14.
Kathleen Donohue 《Oecologia》1997,110(4):520-527
A factorial design of three densities of siblings at three local distances from seed parents was employed to distinguish
effects of density from effects of dispersal distance on lifespan and fruit production of Cakile edentula var. lacustris, a plant with heteromorphic seeds. The segmented fruits produce two seed types: proximal and distal, with distal seeds having
greater mass and greater dispersibility. Effects of longer distances (0.5 km and 30 km) on lifespan and fruit production were
investigated using plants at low density. The prediction was tested that the greater seed mass of distal seeds increases fitness
when seeds are dispersed into sites of unknown quality away from the home site or when seeds are dispersed to low density.
High density caused earlier mortality and lower probability of reproduction. Distance from the maternal plant did not influence
lifespan or reproduction at distances of 15 m or less, but lifespan was longer 0.5 km from the home site. No interaction was
detected between the effects of density and distance on either lifespan or total fitness. Environmental conditions that influence
fitness did not vary as a function of dispersal distance in this system, and favorable conditions at the home site did not
persist between generations. Therefore, selection on dispersion patterns in natural conditions is likely to be through effects
of density rather than dispersal distance. Proximal seeds had greater reproduction than distal seeds at the home site, and
distal seeds had greater reproduction at the more distant sites (but not the most distant site), as expected, but these performance
differences could not be attributed to differences in mass between the two seed types. Reduced seed mass was favored at the
most distant site, but larger seed mass was favored most strongly at low density. Seeds that are dispersed to low density
are larger, suggesting that although kin selection may limit the effectiveness of individual selection to increase seed mass
under conditions of sibling competition, density-dependent individual selection on seed mass, rather than distant-dependent
selection, also contributes to the observed associations among seed type, seed mass and dispersal ability.
Received: 21 October 1996 / Accepted: 4 December 1996 相似文献
15.
M. Kato A. Aoyama F. Naruse T. Kobayashi N. Tsukagoshi 《Molecular & general genetics : MGG》1997,254(2):119-126
Using AnCP (Aspergillus nidulans CCAAT-binding protein) as a CCAAT-specific binding factor model, the possibility that one factor is able to recognize CCAAT
sequences in several different genes in A.␣nidulans was examined. DNase I protection analysis showed that AnCP specifically bound to CCAAT sequence-containing regions comprising
21 to 36 bp of the taa, amdS and gatA genes. Furthermore, replacement of the CCAAT sequence with CGTAA was found to abolish the binding of AnCP and to have an
inhibitory effect on taa promoter activity. This clearly demonstrates a positive function of the CCAAT element. However, amylase was induced by starch
and repressed by glucose in a CCAAT-box disruptant, as in wild-type cells.
Received: 28 June 1996 / Accepted: 7 October 1996 相似文献
16.
In order to test whether an increased export of carbohydrates by leaves and starch mobilization are critical for floral transition
in Arabidopsis thaliana, the Columbia ecotype as well as its starchless mutant pgm and starch-in-excess mutant sex1 were investigated. Induction of flowering was achieved by exposure of plants to either one long day (LD) or one displaced
short day (DSD). The following conclusions were drawn: (i) Both the pgm and sex1 mutants have a late-flowering phenotype in days shorter than 16 h. (ii) When inductive treatments cause a large percentage
of induced plants, there is always a large, early and transient increase in carbohydrate export from leaves. By contrast,
when an inductive treatment results in only a low percentage of induced plants (pgm plants exposed to one DSD), the export of carbohydrates from leaves is not increased, supporting the idea that phloem carbohydrates
have a critical function in floral transition. (iii) Starch mobilization is not required to obtain an increased carbohydrate
export when induction is by one LD (extended period of photosynthesis), but is absolutely essential when induction is by one
DSD (period of photosynthesis unaffected). (iv) Floral induction apparently increases the capability of the leaf phloem-loading
system.
Received: 27 August 1997 / Accepted: 6 March 1998 相似文献
17.
When heterospecific seabirds are part of a nesting colony, there may be less opportunity for conspecifics to come in direct
contact with each other, resulting in lower intraspecific aggressiveness. To determine if individuals spend less time in aggressive
behavior when nesting in conspecific rather than heterospecific groups, we compared the behavior of black skimmers (Rhynchops niger) nesting with gull-billed terns (Sterna nilotica) in three mixed species subcolonies to those of black skimmers in three single species subcolonies. In contrast to our predictions,
black skimmers spent significantly less time in aggressive behaviors when nesting in single species subcolonies than when
nesting with heterospecifics. Although skimmers in mixed species subcolonies tended to have more aggressive interactions with
skimmers than terns, this may be a function of subcolony composition; the proportions of aggressive interactions with conspecifics
were similar to the proportions of conspecifics in each subcolony. However, within the mixed species subcolonies, skimmers
that nested nearer to terns were involved in aggressive interactions significantly less than skimmers that nested closer to
conspecifics. Also, skimmers nested closer to their nearest neighbor when it was a gull-billed tern than when it was another
skimmer. Regardless of which species they nested closest to, skimmers were more aggressive towards other skimmers than to
terns within the mixed species subcolonies. Distance to nearest neighbor's nest did not differ significantly between the colony
types, and did not seem to influence the duration of aggressive activity in the single species subcolonies. In the mixed species
subcolonies, however, the time spent in aggressive behavior increased as the distance to nearest neighbor increased. It appears
that of the several benefits that have been proposed of mixed species colonies, reduced time spent in conspecific aggression
is not among them. However, within a mixed species colony, an individual can reduce time spent in aggressive interactions
by nesting near heterospecifics.
Received: 16 September 1996 / Accepted: 24 February 1997 相似文献
18.
W. Li P. W. Sorensen 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1997,180(4):429-438
(1) Electro-olfactogram recording was used to determine whether the olfactory epithelium of adult sea lamprey is specifically
sensitive to bile acids, some of which have been hypothesized to function as pheromones. Ten bile acids were selected from
38 which had already been pre-screened for olfactory activity. These compounds were first tested on their own, then as adapting
stimuli, and finally as components of mixtures (2) The lamprey-specific bile acids, petromyzonol sulfate and allocholic acid,
were the most potent compounds tested. Five other bile acids were also detectable at picomolar concentrations. Petromyzonol
sulfate had a distinctive dose-response curve. (3) Cross-adaptation demonstrated that sensitivity to bile acids is attributable
to at least four independent classes of olfactory receptor sites and that both the nature and position of conjugating group(s)
are critical to receptor specificity. Notably, petromyzonol sulfate has its own highly specific and independent receptor site.
The situation for unconjugated bile acids was more complex and there appeared to be several sub-classes of receptor sites
for these compounds. (4) Mixture studies largely confirmed the cross-adaptation results, describing receptor site independence
for the same four sets of odorants. Mixture enhancement was also seen when expected and there was no evidence of mixture suppression.
(5) Together, these data demonstrate that conspecific bile acids are discriminated by the olfactory epithelium of the sea
lamprey, supporting the possibility that these compounds may function as migratory pheromones.
Accepted: 23 November 1996 相似文献
19.
We studied the effects of host plant hybridization on the survival and mortality of the leaf-mining moth Phyllonorycter salicifoliella on hybrid and parental willow plants in the field and in a common garden experiment. P. salicifoliella survival differed significantly among three willow taxa in the field in 1994 but not in the field in 1995 or in the common
garden. Parasitism by eulophid wasps differed significantly among taxa in 1994 and appeared to account for the variation in
their survival. In the field in 1995, host feeding predation varied significant among taxa. The theory of tritrophic interactions
predicts that plant genotype can affect natural enemy impact, and this study supports this prediction. Significant variation
in survival and eulophid parasitism was also found among genotypes within taxa in the field in both years and in the common
garden experiment. The common garden results show that genetic differences in plants affect the herbivore-parasitoid interaction.
Variation among years in the patterns of survival and causes of mortality among field plants suggest that genotype by environment
interactions may be important.
Received: 1 March 1996 / Accepted: 4 November 1996 相似文献
20.
Life-strategy shift by intraspecific interaction in Daphnia magna : change in reproduction from quantity to quality 总被引:2,自引:0,他引:2
In Daphnia magna, high animal density causes a mutual intraspecific influence, called life-strategy shift by intraspecific interaction (LiSSII).
We investigated mothers (F0), living singly or in groups of four per 50 ml, and their F1 offspring. Clutch sizes of F0 daphnids living in groups were smaller than those of singly living ones. However, the F1 neonates were bigger in size, had higher dry weights and contained more lipids. They were also able to survive longer starvation
periods. If these F1␣daphnids were again kept in groups of four, the effects of LiSSII on some life-history parameters were stronger. As compared
to group-living F0 daphnids, juvenile development time was prolonged from 7.5 to 10.0 days. In contrast, body size was reduced and the further
reduction in offspring number was slight. The F2␣neonates exhibited the same change towards bigger size and higher dry weight as observed in the F1. In contrast F1 daphnids, that were the offspring of daphnids living in groups but were kept singly were bigger and produced more offspring
than single daphnids that were the offspring of daphnids kept singly. The neonates of the former were bigger in size and heavier.
It is suggested that for the F0 generation the ecological significance of the LiSSII effects is an increase in both the parent and offspring survival probability
when food is limited. LiSSII acts before food conditions deteriorate seriously. Daphnids affected by LiSSII invest less of
their biomass into offspring. Offspring release is well-timed and quality is better, at the expense of quantity. Under favourable
environmental conditions, F2 daphnids that are the offspring of mothers affected by LiSSII appeared well adapted to fast recolonisation when living at
low density.
Received: 18 December 1995 / Accepted: 21 November 1996 相似文献